Railroad retarders control the speed of railroad cars in a marshalling yard. Cars sent over the hump of the yard gain speed as they roll down the hump and are routed via a number of switches to an appropriate track for coupling to other cars on that track. The speed of the cars vary depending on the weight of the car, the speed it is sent over the hump, the number of switches and length of track it needs to traverse, the friction in the wheel bearings of the car, and various other factors. Controlling the speed of the cars is important to ensure the cars arrive at the desired track with an appropriate amount of speed to couple with the other cars. Too little speed, and the car will not make it where they need to go with enough speed to couple with the other cars on the track. Too much speed, and the car will jump the track or damage the coupling mechanisms.
A problem with conventional pneumatic retarder valves is that they are difficult to maintain. Diagnosing the source of a problem such as the malfunctioning component is difficult. The wrong components are frequently replaced in a trial and error effort to fix the valve. This results in great expense and frustration, and dramatically increases down time.
Another problem with conventional pneumatic retarder valves is the difficulty adjusting the upper and lower limits of the various pressure settings for the valve (LIGHT, MEDIUM, HEAVY and EXTRA-HEAVY). Some valves require the use of a very small screw driver to adjust variable resisters that form the source of the reference voltages that dictate the desired pressure limits for activating the opening and closing of the valve.
A further problem with conventional pneumatic retarder valves is that it is difficult to verify whether or not the pressure transducer is providing accurate actual retarder pressure information to the valve. The electric signal or pressure data sent by the transducer to the circuit board is difficult to measure. Although an alternate gage can be used to determine the actual pressure from the retarder cylinders that is being received at the retarder valve, there is no easy way to verify that the transducer signal is sending a signal to the circuit board that accurately corresponds to the actual retarder pressure. Instead of simply replacing a failing or faulty pressure transducer, field personnel attempt to correct the pressure anomalies by adjusting other components such as the variable resisters that set the pressure limits, which fails to correct the underlying problem, can lead to other operational problems in the retarder valve and can lead to accident and injury.
A still further problem with conventional pneumatic retarder valves is their electrical systems. The systems are polarity sensitive and can be damaged by inadvertently switching the positive and negative leads. Separate 12 and 24 VDC assemblies are also needed depending on the input voltage. Power surges such as by lighting strikes can also easily damage the electrical system.
A still further problem with conventional pneumatic retarder valves is that the electronics are difficult to replace. A lightning strike can shut down the control valve for a long time.
A still further problem with conventional pneumatic retarder valves is that they include valves and other components that require frequent lubrication and other maintenance due to the harsh chemicals found in marshalling yards.
A still further problem with conventional pneumatic retarder valves is that they include a large amount of piping and fittings. These components frequently leak the pressurized air they are meant to contain. This leaking wastes air, causes the yard compressors to run more frequently, and reduces the capacity of the pressurized air system for the yard.
A still further problem with conventional pneumatic retarder valves is that many components are exposed to possible damage by parts being dragged by the railroad cars, the environment and rodents.
The present invention is intended to solve these and other problems.